The Fenrir didn't put Leegaain in his eyes. The old lizard was weaker than him, both physically and magically. Salaark was considered the strongest of the six original Guardians but now she wasn't his match.
He had turned into an Empowered Abomination that bore the appearance of his old self, the same he had back on Earth. Solus was the only one that could recognize it thanks to Lith's memories from his first life.